The final act of “Einstein on the Beach,” set on a giant grid complete with moving elevators, erupts with a stream of chanted numbers, an atomic explosion and its aftermath. Photo: Lucie Jansch (2)

A young, tuxedoed Einstein and his lover share a loaded moment on a train. (Lucie Jansch)

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There’s nothing to understand in “Einstein on the Beach,” nothing to “get.”

And as the revival of this 1976 masterpiece shows, that’s OK. As conceived by composer Philip Glass, director Robert Wilson and choreographer Lucinda Childs, this is opera as massive head trip. You just give in to it, for 4 1/2 uninterrupted hours.

Nominally inspired by the frizzy-haired genius, “Einstein” is no soup-to-nuts biography. Don’t expect a linear plot or a physicist belting arias about how everything’s relative. There isn’t a beach, either, beyond a conch shell in the foreground.

The show is divided into several stand-alone scenes — plus two lengthy, full-on ballets — that touch on seemingly unrelated things like lovers on a train and a trial, complete with a man and a child in judges’ wigs. Also there’s a rocket ship, and everyone wears white shirts with black suspenders.

If there’s a connection to Einstein, it’s in the way the show rethinks time and space, juxtaposing cosmic grandeur and a manic attention to details. Glass and Wilson’s respective styles have calcified into clichés over the decades, but here they inspire awe.

Everything is locked into circular patterns that evolve in barely perceptible increments, creating a hypnotic and oddly addictive effect.

Add many instances of the chorus and the performers repeating numerals again and again, and you can see why one of Wilson’s inspirations was an autistic man, poet/artist Christopher Knowles. (Much of the sparse libretto comes from Knowles’ “typings,” compulsively listing the DJs on WABC’s schedule, or looping references to Crazy Eddie.)

The result is entrancing rather than tedious, like watching the opposite of a time-lapse video: Instead of noticing things because they are sped up, you notice them because they are slowed down or repeated many times.

When featured performer Kate Moran sing-songs over and over about going to a “prematurely air-conditioned supermarket” — she sounds eerily like Laurie Anderson — she introduces minute changes in each repetition. Just as virtuosic is the violinist Jennifer Koh, who performs a pair of devilishly tough solos on the edge of the stage, wearing an Einstein fright wig.

But individual contributions are subsumed in the whole. “Einstein” perfectly illustrates Wagner’s concept of “Gesamtkunstwerk”: a total artwork where music and words, choreography and staging, costumes, lights and sets are impossible to separate.

Which adds another reason to head to BAM this week.

While they no longer perform in it — Glass used to be in the pit, both Wilson and Childs danced onstage — this is likely the last time all three creators directly supervise a revival, and the miraculous equilibrium that is “Einstein on the Beach” will be no more. Catch it while you can.